With increasing speed, axial load and quantity of rail traffic, railroad rails are subjected to increasing wear and fatigue and the service life of such rails is commensurately decreasing. The whole length quenching process has been developed in order to improve the useful properties and life of railroad rails and thereby to meet the requirements of railway traffic by providing rails of higher wear and fatigue resistance. Japanese Patent No. 55-23885 describes in detail a heat treatment process of manufacturing high strength rails and represents current improved rail manufacturing processes. However, the disadvantages of this Japanese process include the following:
(1) non-uniform strength of the rail head after heat treatment; PA1 (2) relatively large longitudinal camber ratio after heat treatment; PA1 (3) comparatively low production speed, and PA1 (4) high consumption of cooling air.